Hollow cast metal valve



7 March 3, 1942. A. T. COLWELL HOLLOW CAST METAL VALVE 4 Shets-Sheet 1 Filed March 1, 1940 Qv IQQ/ w 0 7x3 W 1% m m m 2 e6 3 .ea lll li EVE-I1 [17F flrchie I ol'we/j March 19.42

A. T., COLWELL 2,274,667

HOLLOW CAST METAL VALVE Filed March 1, 1940 4 Sheet -g 2 ilIum 'm] a;

March 3, 1942. A. T. COLWELL HOLLOW CAST METAL VALVE Filed March 1, 1940 4 Sheets-Sheets f3 Prior Ari Eryecf Valve March 3, 1942. A 'LW LL 2,274,667

HOLLOW CAST METAL VALVE Filed March 1, 1940 4 Sheets-Shed; 4

1 L Jattf 2 4/1/14";

m Zflz/EnZU-F Y AFC/7J6 7: C0]we]] Patented Mar. 3, 1942 UNITED STATES YPATENT orrlca HOLLOW CAST METAL VALVE Archie T. Colwell, Cleveland, Ohio, assignor to Thompson Products Incorporated, Cleveland, hio,acorporation of Ohio Application March 1, 1940, Serial No. 321,635

1 2 Claims.

This invention relates to hollow castpoppet valves for internal combustion engines and more specifically relates to cast metal poppet valves having hollow head and stem portions.

This application is a continuation-in-part of my co-pending application entitled: "Hollow cast metal valve and method of making same," Serial No. 262,091, filed March 16, 1939.

Hollow poppet valves are usually prepared by metal working operations such asforging. The forging operations are expensive and many desirable metals for poppet valves do not lend themselves to the forging processes because they are very diflicult to forge and, in many cases, cannot be forged at all. Furthermore; forged hollow valves always contain numerous wrinkles in the throat between the head and stem cavities. It is almost impossible to remove these wrinkles and they form loci for fatigue failure. Such wrinkles are entirely avoided in cast valves.

In addition, forged hollow head and stem valves have a sharp corner between the head and stem cavities caused by drilling or reaming the stem cavities. In addition, tool marks or scratches caused by reaming tools or drills in the valve cavities effect real dangers as fatigue loci during use of the valves. It has never proved feasible to grind the interior of a forged hollow valve; consequently this interior must be polished with abrasive papers and there is no positive way of knowing when the scratches have been completely removed. In addition, of course, the polishing operations are very expensive.

Cast valves, on the other hand, can be made with smoother cavity surfaces than can be obtained in a reamed finish. The polishing time is thus materially reduced and any remaining marks will be in the form of pits, and not circumferential grooves which are much more dangerous from a fatigue standpoint.

Thus the cast valves are safer, have longer operating lives, and are cheaper to produce.

According to this invention hollow poppet valvesare formed by casting molten metals tothe desired external shape and by forming the cavity in the head and/or stem at the same time with suitable cores. The castings of this invention so closely approximate the desired final valve shape that very little machining or grinding is necessary. v

Since hollow poppet valves must have uniform walls, it is necessary that the core member for the valve castings be suspended in the valve cavity of a mold so as to be equally spaced from the cavity walls at each portion of the cavity unless the cast metal is-machinable to enable turning down the valve exterior into concentricity with the cavity. While the valve head may have walls of diiferent thickness than the valve stem, one side of the valve head should not be thicker than the other side, nor should one side of the valve stem be thicker than the other side. According to this invention, the core member is provided with a head portion and a stem portion'that is longer than the stem of the cast valve. The mold is formed with a stem end receiving cavity for the core in axial alignment with the valve cavity in the mold. This stem end receiving cavity snugly seats the end portion of the core stem projecting beyond the valve cavity of the mold and suspends the core in proper spaced relation from the walls defining the mold cavity. Sand or metal molds can be used. The molds can be stationary or mounted for centrifugal rotation. v

The core is made of the usual core material such as core sand and binder molded to shape and baked. A feature of the invention includes reinforcing the core with a metal rod having a pronged end. The rod extends axially through the core and the pronged end thereof spreads out into the core head for holding the core material together. The pronged end of the rod is resilient and readily withdrawn through the valve stein. It is. then, an object of the invention to provide hollow cast metal poppet valves. A further object of the invention is to provide cast poppet valves having head and stem cavities whose surfaces are free from wrinkles and scratches such as are always found in forged valves.

A further object of the invention is to provide a hollow stem and head poppet valve casting with a worked-down or wrought stem end of increased strength.

A still further object of the invention is to provide a cast metal hollow poppet valve having head andstem cavities and a thick throat portion joining the head andstem cavities.

A further object of the invention is to pro-. vide'a cast hollow head and stem poppet valve having a cast-in circumferential groove around the head thereof adapted to receive a hard surfacing material to form a seat thereon.

A further object of the invention is to provide a hollow poppet valve casting with 'a boss on the head thereof providing a lathe centering point seat.

Other and further objects of the invention will become apparent to those skilled in the art from the following detailed description of the annexed sheets of drawings, which disclose preferred embodiments of the invention.

On the drawings:

Figure -1 is a top plan viewof a pair of permanent molds mounted in axial alignment for cen- Each cope 12 of the molds Ill and H has a complementary semi-cylindrical pour hole I" extending downwardly from the top thereof at the inner ends of the molds. The pour hole sections communicate at their bottoms with gate holes l8 joining the pour hole with the mold cavities l5.

As best shown in Figure 2, the molds l0 and l lare bolted in axial alignment on the platform IQ of a centrifugal device by means of bolts such as 2|. The platform l9 can be rotated at a desired speed by the motor 22 of the centrifugaldevice.

Core members 23 are mounted in the molds Ill and II in spaced relation from the walls of the mold-cavity l5. These cores 23 have mushroom- Figure 7 is ahorizontal cross-sectional view taken along the line VII-V11 of Figure 6.

Figure 8 is a longitudinal crossesectional view of a valve casting formed in the mold shown in Figures 5 to 7 inclusive.

Figure 8a is a diagrammatic cross-sectional view of a valve casting as shown in Figure 8 and illustrating the machining of the casting to render the outside thereof concentric with the cavity therein.

Figure 9 is a longitudinal cross-sectional view of a core used in the mold shown in Figures 5 to' '7 inclusive.

Figure 10 is a longitudinal cross section of a finished valve made from the casting shown in Figure 8. I

Figure 11 is a longitudinal cross-sectional view of a valve casting formed in the mold shown in Figures 1 and 2.

Figure l2 is a longitudinal cross-sectional view of a, finished valve formed from the casting shown in Figure 11.

Figure 13 is a longitudinal cross-sectional view of a prior art forged valve blank,

Figure 14 is a longitudinal cross-sectional view of a modified form of cast valve blank according tothis invention.

- Figure 15 is a longitudinal cross-sectional view I of a finished valve made from the cast blank shown in Figure 14. a

Figure 16 is an elevational view of a half section of a green sand mold for forming a hollow stern-solid head valve blank casting according to this invention.

Figure 17 is a longitudinal cross-sectional view of a valve blank casting formed in the mold shown in Figure 16 and illustrating, in dotted lines, an insert thimble seated in the stem cavity.

Figure 18 is a side elevational view of a core usedin the mold of Figure 16.

Figure 19 is a longitudinal cross-sectional view of a finished valve made from the cast blank 01 Figure 17.

As shown on the drawings:

In Figures 1 and 2 the reference numerals Ill and II designate generally complementary molds each composed of cope and drag sections I2 and l3 respectively. The copes and drags of each mold In and H are held together by means of bolts such as M. The molds l0 and I I are of the permanent or metal type.

Each mold l0 and H defines a valve shaped cavity I5 therein and axially aligned core-receiving cavities I6.

shaped head portions 23a and elongated stem portions extending from the head 23a axially through the mold cavities Hi. The ends 23b of the stems-are snugly seated in the cavities I6 of the molds. In this manner the cores 23 are suspended in the moldcavities.

Reinforcing rods 24 can be inserted into the centers of the cores when the cores are prepared for reinforcing the cores. The rods 24 are preferably cross-split at one end thereof and four prongs 24a, 25b, 24c, and 24d are bent outwardly as best shown in Figures 3 and 4. The pronged ends of rods project into the heads 23a of'the cores to'hold the core material together even under the centrifugal force of the whirling operation.

In assembling the mold for the casting operation the copes I2 are removed and the mold I3 and the complementary cavities l6 of the copes clamp 'the cores in position to hold the same in spaced relation from the valve-shaped mold cavities l5. The pair of molds l0 and H are then mounted on the platform IQ of the whirling device 29 and molten metal 25is poured into the pour hole I! from which it flows through the gate holes l8 into the mold cavities. The platform I9 is rotated by the motor 22 thus forcing the metal 25 outwardly to fill up the entire mold cavities IS. The centrifugal action drives out all of the air and gas in the cavities and the molds are rotated until the metal solidifies. The motor 22 is then stopped and the molds are opened. The gates are cut or broken 0!! and two valve castings 25 are removed. The valve castings 26 have the cores 23 therein. These cores are readily removed since the cores are frangible and the pronged ends of the reinforcing rods will collapse as the rods are retracted through the stems of the castings 26.

, As best shown in Figure 11, the casting 28 has a headportion 27 provided with a mushroomshaped cavity 21a and a stem portion 28 extending from the head portion 21 and provided with a cylindrical cavity 28a mergingwith the cavity .cavity 32 is partially filled with a cooling material such as metallic sodium 33. The thickened portion 30 of the casting 2G is worked down to form the solid end 34 of the stemof the valve 3|.

This solid portion 34 seals the cavity 32 and preferably has an annular recess 35 cut in the side -thereof for receiving a retainer collar (not shown). The centering lug 29 is ground or cut off of the casting to produce a smooth head for the valve 3!.

The cavities 21a and 28a of the casting 26 need not be ground to form the cavity 32 of the finished valve but it is advisable to polish the cavity 28a in the stem 28' of the casting 26 with emery cloth and sandblast the cavity 21a in the head 27 of the casting 26.

As shown in Figures to 7, a stationary vertical mold 40 can be used to form cast valves according to this invention in place of the rotary horizontal molds shown in Figures 1 and 2.

The mold 48 is composed of two complementary metal halves 4! and 42 secured together by means of dowel pins or bolts 43. Each mold sect-ion 4| and 42 has a complementary cavity in its inner face which together define a conical pour hole 44 in the top of the mold, a gate hole 45 joining the bottom of the pour hole 44 with a poppet valve shaped molding cavity 46, and a core suspending hole 41 axially aligned with the cavity 46 but extending above the gate 45.

A core member 48 having a mushroom-shaped head portion 49 and an elongated stem portion 50 extending from the head portion 49 is provided for forming a cavity in the cast valve.

As shown in Figure 6 the stem 50 of the core 48 is longer than the valve-forming cavity 46 and is of the same diameter as the hole 47. The end of the stem isthus snugly received in the hole 4'! so that the cavity-forming portion of the core is suspended in spaced relation from the walls of the mold-forming cavity 46.

As shown'in Figures 6 and 9, the core 48 is premolded in'the shape of the desired cavity in the cast valve and need not be provided with a reinforcing rod. The core can be composed of the usual core sand and binder and is baked to form a hard, cohesive mass.

When the mold sections 4! and 42 are clamped together by means of the bolts or dowel pins 43, the end of the stem 50 of the'core will be securely clamped in position in the hole 41 provided in the mold. This will automatically suspend the main body of the core in the proper spaced relation from the walls defining the valve cavity 45. As shown in Figure 6, the gate hole 45 has a portion 45a extending around the project ing stem 50 of the core 43 so as to freely join the cavity 46 with the pour hole 44.

Molten metal is introduced into the pour hole 44 and flows downwardly by gravity to fill the entire cavity 48. The mating faces an; and 42a of the mold sections 4| and 42 are purposely left in a rough condition so that air can escape along the joint between the mold sections as the surfaces of the casting,

resulting casting 60 since it iscomposed of sand or other frangible material.

In the event that the head and stem cavities in the casting 60 are not concentric with the outer the cavities are first polished to a finished condition without attempting to render th same concentric with the outside surface'of the casting. The casting 60 is then inserted in a lathe having a driving plug P inserted into the open end of the stem cavity 62a. The centering pin C of the lathe is then pierced into the lug 63 of the casting. This lug is large enough in diameter to take the machining center even though the cavities are eccentric with the outside surface of the casting. In this manner the rotating axis of the casting is located from the finished hole in the stem. As shown in Figure 8 the outside surface of the casting is somewhat eccentric to the cavities but is turned down to strict concentricity by a lathe or grinding operation. In other words, all that is necessary is the correct location of the axis of rotation of the casting followed by a turning down of the outer surface of the casting into concentricity with the cavities therein. hn

A lathe-cutting too ay be used to cut down the casting or a grinding operation maybe relied upon in the event that the casting alloy is not machinable.

The casting 60 then can be ground to remove the centering lug 63 and other casting irregularimolten metal is poured into the mold cavity. The

molten metal fills the entire cavity around the core 48 to provide a valve casting 60 (Figure 8). The casting 60 has a mushroom-shaped head portion 6| with a cavity 6Ia therein and an elongated cylindrical stem portion 62 extending axlally from the head portion and provided with a cylindrical cavity 62a merging with the head cavity Ma. The head 6| has a centering lug Won the center thereof.

The mold 40 is preferably coated with graphite before th core and molten metal are introduced therein. The core is readily removed from the ties to produce a finished poppet valve 64 as shown in Figure 10. The valve 64 has a cavity 65 in the head and stem.portion thereof. The

cavity 65 is partially'filled with a cooling material such as metallic sodium BGand the open cap 61 Welded,. brazed, or force-fitted into the en end of the stem is closed by a The stem can be provided with an annular groove 0r recess 68 in the end portion thereof for receiving a retainer collar (not shown).

The valve 64 can becompletely formed from the casting 60 without metal-working operations, since all of the finishing can be done by grinding. This makes possible the use of non-machinable alloys for producing valves according to this invention.

Suitable metals for fo-rmingthe valve castings of this invention are: nickel, chromium, and iron alloys such as Nichrome steels; nickel, molybdenum and iron alloys such as Hastelloy. steels; non-ferrous nickel-chromium alloys such as Brightray and cobalt, chromium and tungsten alloys such as Stellite. It should be understood, of course, that the invention .is not limited to the use of such alloys but a number of these very hard alloys do not lend themselves to forging and at the same time are highly desirable metals for poppet valves. This invention now makes possible the use of these non-forgeable and even nonmachinable alloys.

In Figure 13 the referencenumeral l0 designates a forged valve blank as is customarily produced by forging operationson a metal billet to produce a hollow poppet valve. As shown in Figure 13, the valve blank H1 has numerous Wrinkles H in the throat between the head and stem cavities. These wrinkles are always present as a result of the swaging operation and it is impossible to completely remove them. The wrinkles 'H are always potential loci for fatigue failure. They ar not present in a casting according to this invention.

As also shown in Figure 13, a sharp corner: 12 is formed in the forged blank in between the head formed around the circumference of the holes. 7

It has never proved feasible to grind the holes in a forged valve blank and, as a result, it must be polished with abrasive paper. There is no positive way of knowing when the tool marks I3 are completely removed. Furthermore, attempts to remove these marks are extremely expensive While the cast valves of this invention can be produced with smoother surfaces than are possible in a reamed finish on a forged blank,-some'pol hing operation may be necessary but the amount of polishing is materially reduced. Furthermore, any marks remaining in the valve cavities will be in the form of pits and not as circumferential grooves 13 which are, of course, much more dangerous from a fatigue standpoint.

The modified cast valve blank 89 shown in Figure 14 can be readily formed according to this invention by the provisionof a'suitable core andmold to define the contour of the blank. The blank 99 is similar to the blank 26 shown in Figure 11 and identical parts have been designated by the same reference numerals. The modified blank 99 has a thickened portion 8I at the throat between the head cavity 21a and the stem cavity 29a. This thickened portion has a. smooth rounded contour in the high temperature zone or throat of the valve and is a desirable reinforcement for the structure. While a thickened portion can be provided in the throat of a forged valve by drilling a tapered hole in the throat, the edge or sharp corner I2 (Figure 13) is always formed. This corner cannot be removed and is a possible danger point or locus for fatigue cranks.

The valve head 21 has a cast-in circumferenan annular recess II3 therearound formed by the annular. projection 98 in the; mold cavity.

tial groove 92 adapted to receive a hard surfacing material to form a seat for the valve head.

As shown in'Figure 15, a sodium cooled hollow head and stem valve 85 is fprmed from the blank 99 by working down the thickened portion 39 'of the blank to form a solid end 34 as described in Figure 12. Parts identical with parts described in Figure 12 are marked with the same reference numerals.

The valve 85 has a Stellite or other wear-resisting metal seat 86 formed in the head thereof by filling up the groove 82 of the blank with Stellite and welding the same to the cast metal. The seat 96 is thus integrally bonded to the valve head 21 by means of a, welded bond 81. The seat metal can be puddled in the groove 82 to. build up the seat.

In Figure 16 the reference numeral 99 designates generally a half-section of a molding flask adapted to cooperate'with a mating half-section to define a complete flask. The flask 99 is filled with green sand 9| which defines a molding cavity 92. The molding cavity 92 has an enlarged stem end portion 93 near the top thereof, an intermediate main stem portion 94 and a head portion 95. The head portion includes a dished bottom 96 with a central recess 91 therein. A 10- calized annular projection 98 extends around the side of the headportion for a purpose to be more fully hereinafter described.

A gate cavity 99 is formed above the enlarged stem portion 93 and communicates with a pour hole I99 in the top of the mold.

- A core suspension cavity IN is formed above the gate cavity.

As shown in Figures 16 and 18 a baked sand ,core I92 is suspended in the mold cavity 92 in spaced relation from the cavity walls. The core I92 has an enlarged top end portion I93 with the upper end thereof snugly seated in the suspension cavity I9I. An elongated cylindrical portion I94 of reduced diameter depends from the enlarged end portion I93 of the core and is recessed as at I95 to define a further reduced diameter portion near the lower end of the core. The bottom of the core is of about the same diameter as the cylindrical portion I94.

As shown in Figure 16 the core is suspended in the molding cavity 92 in-spaced relation from the cavity walls and the bottom of the core is spaced above the dished bottom 96 of the cavity.

Molten metal is poured through the pour hole I99 to fill the molding cavity 92 and form a casting I96 as shown in Figure 17. The core, of course, is removed from the open stem end of the casting. The casting I96 has a thickened stem end portion I9'I provided with an enlarged passageway I99 therein formed by the enlarged portion I93 of the core. A main stem portion I99, of reduced diameter, extends from the thickened portion I91 and has a passageway II9 casting. This reduced passage is at the throat portion of the valve and the resulting valve has a. thickened throat portion I I I of smooth contour. The valve blank I96 hasa solid head II2 with A centering lug Ill projects from-the central portion of thesolid valve head and is formed in the recess 91 of the. mold cavity.

As shown in dotted lines in Figure 17 a metal thimble H5 is inserted in the stem cavity III of the valve blank and has an outturned shoulder I-I5a bottomed against the shoulder formed at the inner end of the passageway I99, e

-As shown in Figure 19, the valve blank I6 is formed into a finished hollow stem solid valve poppet valve I29. The valve I29 has a solid 'stem end I H worked down from the thickened portion I9I of the blank I96 and a metal insert I22 formed from the thimble H5- The thimble I22. has-a collapsed end portion I220. seated in the solid stem end I2I. This portion I220. is formed from the open end of the thimble during the working'down of the thickened end portion I'9I of the blank.

A Stellite or other hard wearable metal alloy tip I23 is welded on the end of the solid stem end I2I.

seat I2'I is welded in the groove N3 of the head.

The resulting valve thus has a hardened stem tip and a hardened valve seat. The head of the valve is solid and the stem of the valve is hollow and partially filled with a coolant such as metallic sodium.

From. the above descriptions it will be under-'- stood that this invention provides castv metal valve blanks having cavities in the stem portions Grooves I24 for retaining collars or the like can be formed in the solid stem end.

thereof and preferably in both the head and stem portions thereof. These blanks are readily made into finished hollow poppet valves. The cast hollow valves of the invention have many material advantages over forged valves. In some embodiments of the invention the working down of a thickened cast stem portion into a solid stem end produces a hollow cast valve with a worked end of increased strength.

It will, of course, be understood that various details of construction may be varied through a wide range without departing from the principles of this invention and it is, therefore, not the purpose to limit the patent granted hereon appended claims.

I claim as my invention:

1. A poppet valve body comprising a hollow I one-piece casting having a mushroom-shaped head with a mushroom-shaped cavity therein and a cylindrical stem projecting from said head with a cylindrical cavity along the length' thereof merging into said mushroom-shaped cavity to define a smooth thickened throat free from wrinkles and sharp corners.

2. A cast hollow stem and head poppet valve having a thickened throat defining wall between the head and stem with an interior surface of smooth contour free from corners and wrinkles.

ARCHIE T. COLWELL. 

